CN102511026A - Display device - Google Patents

Abstract

A plurality of 1 st sensor pixel circuits and 2 nd sensor pixel circuits are arranged in each pixel region, and detect light during a predetermined detection period, and otherwise hold the amount of light detected. The backlight is turned on 1 time at a predetermined time in a 1-frame period, and a detection period (A1) when the backlight is turned on and a detection period (A2) when the backlight is turned off are set 1 time each in the 1-frame period. The 1 st sensor pixel circuit is reset at the beginning of the period (a1) and detects light during the period (a 1). The 2 nd sensor pixel circuit is reset at the beginning of the period (a2) and detects light during the period (a 2). The readout from the 2 kinds of sensor pixel circuits is performed in parallel and in line order except for the periods (a1) and (a 2). A difference between the amount of light when the backlight is turned on and the amount of light when the backlight is turned off is obtained using a differential circuit provided outside the sensor pixel circuit. Thus, a display device having an input function independent of the light environment can be provided.

Description

display device

technical field

The present invention relates to a display device, in particular to a display device in which a plurality of photosensors are arranged in a pixel area.

Background technique

Conventionally, a display device is known in which a plurality of photosensors are provided on a display panel to provide input functions such as a touch panel, pen input, and a scanner. In order to apply this method to mobile devices used in various light environments, it is necessary to exclude the influence of the light environment. Therefore, a method is also known in which a component that depends on the light environment is removed from a signal detected by an optical sensor to obtain a signal that should be originally input.

Patent Document 1 describes the case where, in an input/output device provided with light-receiving elements corresponding to each display element, the backlight is turned on and off once in one frame period, in order to obtain data from all light-receiving elements in one frame period. The amount of light while the backlight is on and the amount of light when the backlight is off are reset and read out in line order for the light receiving element.

FIG. 22 is a diagram showing the timing of turning on and off of the backlight described in Patent Document 1, and the timing of resetting and reading out the light receiving elements. As shown in FIG. 22 , the backlight is turned on in the first half of one frame period and turned off in the second half. While the backlight is on, resetting to the light-receiving element is performed line-sequentially (solid-line arrow), and then readout from the light-receiving element is line-sequentially performed (dotted-line arrow). Resetting and reading of the light-receiving element are performed similarly while the backlight is turned off.

Patent Document 2 describes a solid-state imaging device including the unit light receiving unit shown in FIG. 23 . The unit light receiving part shown in FIG. 23 includes one photoelectric conversion part PD and two charge storage parts C1 and C2. When receiving both object-reflected light and external light from the light emitting device, the first sampling gate SG1 is turned on, and charges generated by the photoelectric conversion portion PD are stored in the first charge storage portion C1. When only external light is received, the second sampling gate SG2 is turned on, and the charges generated by the photoelectric conversion part PD are stored in the second charge storage part C2. By obtaining the difference between the amounts of charges stored in the two charge storage units C1 and C2, the amount of light reflected from the object by the light from the light emitting device can be obtained.

prior art literature

patent documents

Patent Document 1: Japanese Patent No. 4072732

Patent Document 2: Japanese Patent No. 3521187

Contents of the invention

The problem to be solved by the invention

Generally, in a display device having a display panel provided with a plurality of photosensors, readout from the photosensors is performed line-sequentially. In addition, the backlight for mobile devices is turned on and off simultaneously for the entire screen.

The input/output device described in Patent Document 1 turns on and off the backlight once in a frame period, resets and reads out during the period when the backlight is on, and does not repeat it during the period when the backlight is off. Perform reset and readout. Therefore, it is necessary to perform reading from the light receiving element within 1/4 frame period (for example, within 1/240 second when the frame rate is 60 frames/second). However, it is actually quite difficult to perform such high-speed readout.

In addition, there is a 1/ Deviation during 2 frames. Therefore, followability with respect to a mobile input varies with the direction of the input. In addition, this input/output device starts reading immediately after the reset is completed, and starts resetting immediately after the reading is completed. Therefore, the lengths and intervals of the backlight-on period and the backlight-off period cannot be freely determined.

Therefore, an object of the present invention is to solve the above problems and provide a display device having an input function independent of light environment.

solutions to problems

A first aspect of the present invention is a display device in which a plurality of photosensors are arranged in a display area, characterized in that it includes:

a display panel comprising a plurality of display pixel circuits and a plurality of sensor pixel circuits;

a light source that is turned on at a prescribed time during 1 frame; and

a drive circuit that outputs a first control signal indicating a detection period when the light source is on and a second control signal indicating a detection period when the light source is off for the sensor pixel circuit, and performs reset and readout for the sensor pixel circuit,

The above sensor pixel circuit includes:

A first sensor pixel circuit that detects light during a detection period when the light source is turned on according to the first control signal, and maintains the detected light amount otherwise; and

The second sensor pixel circuit detects light during the detection period when the light source is turned off according to the second control signal, and maintains the detected light amount in other cases,

The drive circuit performs readout from the first sensor pixel circuit and the second sensor pixel circuit in line order other than the detection period when the light source is turned on and the detection period when the light source is turned off.

A second aspect of the present invention is characterized in that, in the first aspect of the present invention,

The above-mentioned light source is turned on once at a predetermined time during one frame,

The detection period when the light source is turned on and the detection period when the light source is turned off are each set once in one frame period.

A third aspect of the present invention is characterized in that, in the second aspect of the present invention,

The drive circuit resets the first sensor pixel circuit at the beginning of the detection period when the light source is turned on, and resets the second sensor pixel circuit at the beginning of the detection period when the light source is turned off.

A fourth aspect of the present invention is characterized in that, in the second aspect of the present invention,

The detection period when the light source is turned on is set immediately after the detection period when the light source is turned off.

A fifth aspect of the present invention is characterized in that, in the second aspect of the present invention,

The detection period when the light source is off is set immediately after the detection period when the light source is on.

A sixth aspect of the present invention is characterized in that, in the second aspect of the present invention,

The detection period when the light source is turned on is the same length as the detection period when the light source is turned off.

A seventh aspect of the present invention is characterized in that, in the first aspect of the present invention,

The display panel further includes a plurality of output lines for transmitting output signals of the first sensor pixel circuit and the second sensor pixel circuit,

The first sensor pixel circuit and the second sensor pixel circuit are connected to different output lines according to types,

The drive circuit performs readout from the first sensor pixel circuit and the second sensor pixel circuit in parallel.

An eighth aspect of the present invention is in the seventh aspect of the present invention,

A differential circuit is further provided that obtains a difference between an output signal of the first sensor pixel circuit and an output signal of the second sensor pixel circuit.

A ninth aspect of the present invention is characterized in that, in the first aspect of the present invention,

The first sensor pixel circuit and the second sensor pixel circuit include:

1 light sensor;

1 storage node that stores charges corresponding to the amount of light detected;

a read transistor having a control terminal electrically connectable to the storage node; and

The switching element for holding is provided on the path of the current flowing through the above-mentioned photosensor, and is turned on/off according to a given control signal,

The holding switching element included in the first sensor pixel circuit is turned on during the detection period when the light source is turned on in accordance with the first control signal, and the holding switching element included in the second sensor pixel circuit is turned on in accordance with the second control signal. Turns on during detection when the light source is off.

A tenth aspect of the present invention is characterized in that, in the ninth aspect of the present invention,

In the first sensor pixel circuit and the second sensor pixel circuit,

The holding switching element is provided between the storage node and one end of the photosensor,

The other end of the aforementioned light sensor is connected to the reset line.

An eleventh aspect of the present invention is characterized in that, in the ninth aspect of the present invention,

The first sensor pixel circuit and the second sensor pixel circuit include the following elements as the holding switching elements:

a first holding switching element provided between the storage node and one end of the photosensor; and

The second holding switching element is provided between the reset line and the other end of the photosensor.

A twelfth aspect of the present invention is characterized in that, in the tenth aspect of the present invention,

The first sensor pixel circuit and the second sensor pixel circuit share one photosensor between the two circuits,

One end of the common photosensor is connected to one end of a holding switching element respectively included in the first sensor pixel circuit and the second sensor pixel circuit, and the other end is connected to the reset line.

A thirteenth aspect of the present invention is characterized in that, in the eleventh aspect of the present invention,

The first sensor pixel circuit and the second sensor pixel circuit share one photosensor between the two circuits,

One end of the shared photosensor is connected to one end of a first holding switching element respectively included in the first sensor pixel circuit and the second sensor pixel circuit, and the other end is connected to the first sensor pixel circuit and the second sensor pixel circuit respectively. Contains one end of the 2nd holding switching element.

A fourteenth aspect of the present invention is characterized in that, in the twelfth aspect of the present invention,

The first sensor pixel circuit and the second sensor pixel circuit share one readout transistor between the two circuits,

A control terminal of the common readout transistor is connected to one end of the common photosensor and one end of a holding switching element respectively included in the first sensor pixel circuit and the second sensor pixel circuit.

A fifteenth aspect of the present invention is a method of driving a display device,

The above display device has: a display panel including a plurality of display pixel circuits and a plurality of sensor pixel circuits; and a light source,

The above-mentioned driving method of the display device has the following steps:

A step of turning on the above-mentioned light source at a predetermined time during one frame;

A step of outputting a first control signal representing a detection period when the light source is on and a second control signal representing a detection period when the light source is off, with respect to the sensor pixel circuit;

A step of detecting light during a detection period when the light source is turned on according to the first control signal using the first sensor pixel circuit included in the sensor pixel circuit, and maintaining the detected light amount otherwise;

Using the second sensor pixel circuit included in the sensor pixel circuit, according to the second control signal, detecting light during a detection period when the light source is turned off, and maintaining the detected light amount in other cases;

Except for the detection period when the light source is turned on and the detection period when the light source is turned off, the steps of reading from the first sensor pixel circuit and the second sensor pixel circuit are performed in line order.

Invention effect

According to the first or fifteenth aspect of the present invention, two kinds of sensor pixel circuits can be used to detect the light quantity when the light source is on and the light quantity when the light source is off, and the difference between the two can be obtained outside the sensor pixel circuit. Thus, an input function that does not depend on the light environment can be provided. In addition, compared with the case where one sensor pixel circuit sequentially detects two kinds of light quantities, the number of readouts from the sensor pixel circuit can be reduced, the readout speed can be reduced, and the power consumption of the device can be reduced. In addition, by performing readout from the sensor pixel circuit outside the detection period, the degree of freedom in determining the timing of turning on and off the light source, and the timing of resetting and reading out the sensor pixel circuit increases. In addition, during the detection period when the light source is turned on, all the first sensor pixel circuits detect light, and during the detection period when the light source is turned off, all the second sensor pixel circuits detect light. Therefore, if the detection period when the light source is turned on and the detection period when the light source is turned off are set close to each other, the discrepancy between the two detection periods can be eliminated, and the followability to the movement input can be prevented from changing depending on the input direction.

According to the second aspect of the present invention, a display device in which the light source is turned on once at a predetermined time in a frame period, and the detection period when the light source is turned on and the detection period when the light source is turned off is set once in each frame period can be obtained. the above effects.

According to the third aspect of the present invention, by resetting the sensor pixel circuits at the beginning of each detection period, it is possible to accurately detect the amount of light in each sensor pixel circuit. Also, by collectively performing resets for the same type of sensor pixel circuits, the same type of sensor pixel circuits can detect light in the same period. In addition, the time required for resetting can be shortened, and the degree of freedom in determining read timing can be increased.

According to the fourth aspect of the present invention, by setting the detection period when the light source is on and the detection period when the light source is off, the difference between the two detection periods can be eliminated, and the follow-up to the movement input can be prevented. change in direction. In addition, by setting the detection period when the light source is turned on immediately after the detection period when the light source is turned off, even when using a light source that takes longer to turn on than to turn off, the light source can be turned on during the entire detection period when the light source is turned on. Bright, improve detection accuracy.

According to the fifth aspect of the present invention, by setting the detection period when the light source is off and the detection period when the light source is on to be close to each other, it is possible to eliminate the difference between the two types of detection periods, and to prevent follow-up with respect to movement input. change in direction. In addition, by setting the detection period when the light source is turned off immediately after the detection period when the light source is turned on, detection errors caused by light leakage in the switching elements included in the sensor pixel circuit can be suppressed.

According to the sixth aspect of the present invention, the difference between the light quantity when the light source is on and the light quantity when the light source is off can be accurately obtained by detecting the light quantity when the light source is on and the light quantity when the light source is off during the same length of time.

According to the seventh aspect of the present invention, by connecting the first and second sensor pixel circuits to different output lines according to the types, and performing readout from the two types of sensor pixel circuits in parallel, the readout speed can be reduced, and the work of the device can be reduced. consumption. In addition, if two kinds of light quantities are read out in parallel and the difference between the two kinds of light quantities is obtained immediately, a memory for storing the first detected light quantity, which is required when sequentially detecting two kinds of light quantities, is unnecessary.

According to the eighth aspect of the present invention, by providing a difference circuit for obtaining the difference between the output signal of the first sensor pixel circuit and the output signal of the second sensor pixel circuit, the amount of light incident when the light source is turned on and the difference between the light intensity and the output signal of the light source can be obtained immediately. The difference in the amount of incident light at the time of extinction does not require a memory for storing the amount of light detected first.

According to the ninth aspect of the present invention, by providing a switching element for holding that is turned on during a specified detection period on the path of the current flowing through the photosensor, it is possible to constitute a first sensor pixel circuit that detects when the light source is turned on. detects light during the period, and maintains the detected light quantity otherwise; and the second sensor pixel circuit detects light during the detection period when the light source is turned off, and maintains the detected light quantity otherwise. Based on the output signals of these sensor pixel circuits, the difference between the light amount when the light source is turned on and the light amount when the light source is turned off can be obtained outside the sensor pixel circuit.

According to the tenth aspect of the present invention, by providing a holding switching element between the photosensor and the storage node, it is possible to configure a sensor pixel circuit that detects light during a predetermined detection period and holds the amount of light detected otherwise, and constitutes a Using this sensor pixel circuit, a first sensor pixel circuit that detects the amount of light when the light source is turned on and a second sensor pixel circuit that detects the amount of light when the light source is turned off are used.

According to the eleventh aspect of the present invention, by providing holding switching elements on both sides of the photosensor, it is possible to configure a sensor pixel circuit that detects light during a specified detection period and holds the detected light amount otherwise, and can configure a sensor pixel circuit using this The sensor pixel circuit is a first sensor pixel circuit that detects the amount of light when the light source is on, and a second sensor pixel circuit that detects the amount of light when the light source is off. In addition, the second holding switching element provided between the photosensor and the reset line is turned off during periods other than the detection period. Therefore, the variation in the potential of the terminal of the photosensor on the side of the first holding switching element due to the current flowing in the photosensor becomes small, and the potential difference applied to both ends of the first holding switching element becomes small. Thereby, leakage current flowing through the first holding switching element can be reduced, fluctuations in the potential of the storage node can be prevented, and detection accuracy can be improved.

According to the twelfth or thirteenth aspect of the present invention, by sharing one photosensor between two types of sensor pixel circuits, the influence of dispersion in the sensitivity characteristics of the photosensor can be eliminated, and the light quantity when the light source is turned on and the time when the light source is turned off can be accurately obtained. difference in the amount of light. In addition, the number of photosensors can be reduced, the aperture ratio can be increased, and the sensitivity of the sensor pixel circuit can be improved.

According to the fourteenth aspect of the present invention, by sharing one readout transistor between the two types of sensor pixel circuits, it is possible to eliminate the influence of dispersion of the threshold characteristic of the readout transistor, and accurately obtain the light quantity when the light source is turned on and the light quantity when the light source is turned off. The difference in the amount of light.

Description of drawings

FIG. 1 is a block diagram showing the configuration of a display device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of sensor pixel circuits in a display panel included in the display device shown in FIG. 1 .

FIG. 3 is a diagram showing the timing of turning on and off of a backlight in the display device shown in FIG. 1 , and the timing of resetting and reading out for a sensor pixel circuit.

FIG. 4 is a signal waveform diagram of a display panel included in the display device shown in FIG. 1 .

FIG. 5 is a diagram showing a schematic configuration of a sensor pixel circuit included in the display device shown in FIG. 1 .

6 is a circuit diagram of a sensor pixel circuit according to the first embodiment of the present invention.

FIG. 7 is a diagram showing the operation of the sensor pixel circuit shown in FIG. 6 .

FIG. 8 is a signal waveform diagram of the sensor pixel circuit shown in FIG. 6 .

9 is a circuit diagram of a sensor pixel circuit according to a second embodiment of the present invention.

FIG. 10 is a diagram showing the operation of the sensor pixel circuit shown in FIG. 9 .

11 is a circuit diagram of a sensor pixel circuit according to a third embodiment of the present invention.

FIG. 12 is a diagram showing the operation of the sensor pixel circuit shown in FIG. 11 .

FIG. 13 is a signal waveform diagram of the sensor pixel circuit shown in FIG. 11 .

14 is a circuit diagram of a sensor pixel circuit according to a fourth embodiment of the present invention.

FIG. 15 is a diagram showing the operation of the sensor pixel circuit shown in FIG. 14 .

16 is a circuit diagram of a sensor pixel circuit according to a fifth embodiment of the present invention.

FIG. 17 is a diagram showing the operation of the sensor pixel circuit shown in FIG. 16 .

FIG. 18 is a signal waveform diagram of the sensor pixel circuit shown in FIG. 16 .

19 is a circuit diagram of a sensor pixel circuit according to a sixth embodiment of the present invention.

20 is a circuit diagram of a sensor pixel circuit according to a seventh embodiment of the present invention.

21A is a circuit diagram of a sensor pixel circuit according to a first modified example of the first embodiment.

21B is a circuit diagram of a sensor pixel circuit according to a second modified example of the first embodiment.

21C is a circuit diagram of a sensor pixel circuit according to a third modified example of the first embodiment.

21D is a circuit diagram of a sensor pixel circuit according to a fourth modification of the first embodiment.

21E is a circuit diagram of a sensor pixel circuit according to a fifth modification of the first embodiment.

21F is a circuit diagram of a sensor pixel circuit according to a sixth modification example of the first embodiment.

21G is a circuit diagram of a sensor pixel circuit according to a seventh modification of the first embodiment.

21H is a circuit diagram of a sensor pixel circuit according to an eighth modification of the first embodiment.

22 is a diagram showing the timing of turning on and off the backlight in a conventional input/output device, and the timing of resetting and reading out of a light receiving element.

FIG. 23 is a circuit diagram of a unit light receiving unit included in a conventional solid-state imaging device.

Detailed ways

FIG. 1 is a block diagram showing the configuration of a display device according to an embodiment of the present invention. The display device shown in FIG. 1 includes a display control circuit 1 , a display panel 2 and a backlight 3 . The display panel 2 includes a pixel area 4 , a gate driver circuit 5 , a source driver circuit 6 and a sensor row driver circuit 7 . The pixel area 4 includes a plurality of display pixel circuits 8 and a plurality of sensor pixel circuits 9 . This display device has a function of displaying an image on the display panel 2 and a function of detecting light incident on the display panel 2 . Next, set x to be an integer greater than 2, set y to be a multiple of 3, set m and n to be even numbers, and set the frame rate of the display device to 60 frames/second.

A video signal Vin and a timing control signal Cin are externally supplied to the display device shown in FIG. 1 . Based on these signals, the display control circuit 1 outputs a video signal VS and control signals CSg, CSs, and CSr to the display panel 2 , and outputs a control signal CSb to the backlight 3 . The video signal VS may be the same as the video signal Vin, or may be a signal subjected to signal processing on the video signal Vin.

The backlight 3 is a light source that irradiates light to the display panel 2 . More specifically, the backlight 3 is provided on the rear side of the display panel 2 and irradiates light to the rear surface of the display panel 2 . The backlight 3 is turned on when the control signal CSb is at a high level, and turned off when the control signal CSb is at a low level.

In the pixel region 4 of the display panel 2 , (x×y) display pixel circuits 8 and (n×m/2) sensor pixel circuits 9 are arranged two-dimensionally. More specifically, x gate lines GL1 to GLx and y source lines SL1 to SLy are provided in the pixel region 4 . The gate lines GL1 to GLx are arranged in parallel to each other, and the source lines SL1 to SLy are arranged in parallel to each other so as to be perpendicular to the gate lines GL1 to GLx. (x×y) display pixel circuits 8 are arranged near intersections of gate lines GL1 to GLx and source lines SL1 to SLy. Each display pixel circuit 8 is connected to one gate line GL and one source line SL. The display pixel circuits 8 are classified into those for red display, green display, and blue display. These three types of display pixel circuits 8 are arranged side by side in the extending direction of the gate lines GL1 to GLx to constitute one color pixel.

In the pixel region 4 , n clock lines CLK1 to CLKn, n reset lines RST1 to RSTn, and n readout lines RWS1 to RWSn are provided in parallel to the gate lines GL1 to GLx. In addition, other signal lines and power supply lines (not shown) may be provided in parallel to the gate lines GL1 to GLx in the pixel region 4 . When reading from the sensor pixel circuit 9 , m selected from the source lines SL1 to SLy are used as power supply lines VDD1 to VDDm, and the other m are used as output lines OUT1 to OUTm.

FIG. 2 is a diagram showing the configuration of the sensor pixel circuit 9 in the pixel region 4 . The (n×m/2) sensor pixel circuits 9 include a first sensor pixel circuit 9a that detects light incident while the backlight 3 is on and a second sensor pixel circuit 9b that detects light incident while the backlight 3 is off. The first sensor pixel circuits 9a and the second sensor pixel circuits 9b have the same number. In FIG. 2 , (n×m/4) first sensor pixel circuits 9 a are arranged near intersections of odd-numbered clock lines CLK1 to CLKn-1 and odd-numbered output lines OUT1 to OUTm-1. (n×m/4) second sensor pixel circuits 9 b are arranged near intersections of the even-numbered clock lines CLK2 to CLKn and the even-numbered output lines OUT2 to OUTm. In this way, the display panel 2 includes a plurality of output lines OUT1 to OUTm for transmitting the output signal of the first sensor pixel circuit 9a and the output signal of the second sensor pixel circuit 9b. The first sensor pixel circuit 9a and the second sensor pixel circuit 9b are divided into types Connect to a different output line.

The gate drive circuit 5 drives the gate lines GL1 to GLx. More specifically, the gate drive circuit 5 sequentially selects one gate line from among the gate lines GL1-GLx based on the control signal CSg, applies a high-level potential to the selected gate line, and applies a low-level potential to the remaining gate lines. Flat potential. Thereby, y display pixel circuits 8 connected to the selected gate line are selected together.

The source drive circuit 6 drives the source lines SL1 to SLy. More specifically, the source drive circuit 6 applies a potential corresponding to the video signal VS to the source lines SL1 to Sly based on the control signal CSs. At this time, the source driving circuit 6 may perform line-sequential driving or dot-sequential driving. The potentials applied to the source lines SL1 to Sly are written into the y display pixel circuits 8 selected by the gate drive circuit 5 . In this way, a desired image can be displayed on the display panel 2 by writing potentials corresponding to the video signal VS to all the display pixel circuits 8 using the gate driver circuit 5 and the source driver circuit 6 .

The sensor row drive circuit 7 drives clock lines CLK1 to CLKn, reset lines RST1 to RSTn, readout lines RWS1 to RWSn, and the like. More specifically, in the display device of the present embodiment, a detection period when the backlight is turned on and a detection period when the backlight is turned off are set once in one frame period (details will be described later). The sensor row driving circuit 7 applies a high-level potential to the odd-numbered clock lines CLK1 to CLKn-1 during the detection period when the backlight is turned on, and applies a high-level potential to the even-numbered clock lines CLK2 to CLKn during the detection period when the backlight is turned off. level potential. In addition, the sensor row drive circuit 7 applies a high-level potential to the odd-numbered reset lines RST1 to RSTn-1 at the beginning of the detection period when the backlight is turned on, and resets the even-numbered reset lines RST1 to RSTn-1 at the beginning of the detection period when the backlight is turned off. A high-level potential is applied to the lines RST2 to RSTn. Thereby, (n×m/4) sensor pixel circuits 9 connected to the reset line to which the high-level potential is applied are reset together.

In addition, the sensor row drive circuit 7 sequentially selects two adjacent readout lines from the readout lines RWS1 to RWSn based on the control signal CSr, applies a high-level potential for readout to the selected readout line, and applies a high-level potential for readout to the remaining readout lines. A low-level potential is applied to the outgoing line. Thereby, m sensor pixel circuits 9 connected to the selected two readout lines are collectively in a readout state. At this time, the source driving circuit 6 applies a high-level potential to the power supply lines VDD1 -VDDm. Thus, a signal corresponding to the amount of light detected by each sensor pixel circuit 9 (hereinafter referred to as a sensor signal) is output from the readable m sensor pixel circuits 9 to the output lines OUT1 to OUTm.

The source driver circuit 6 includes a differential circuit (not shown) that obtains the difference between the output signal of the first sensor pixel circuit 9a and the output signal of the second sensor pixel circuit 9b. The source driver circuit 6 amplifies the difference in light intensity obtained by the differential circuit, and outputs the amplified signal as a sensor output Sout to the outside of the display panel 2 . In this way, light incident on the display panel 2 can be detected by reading sensor signals from all the sensor pixel circuits 9 using the source driver circuit 6 and the sensor row driver circuit 7 . The display device shown in FIG. 1 performs the following primary driving in order to detect light incident on the display panel 2 .

FIG. 3 is a diagram showing the timing of turning on and off of the backlight 3 , and the timing of resetting and reading out for the sensor pixel circuit 9 . As shown in FIG. 3 , the backlight 3 is turned on once at a predetermined time in one frame period, and is turned off during periods other than the predetermined time. More specifically, the backlight 3 is turned on at time tb within one frame period and turned off at time tc. In addition, all the first sensor pixel circuits 9 a are reset at time tb, and all the second sensor pixel circuits 9 b are reset at time ta.

The first sensor pixel circuit 9 a detects light incident during a period A1 (a lighting period of the backlight 3 ) from time tb to time tc. The second sensor pixel circuit 9 b detects light incident during a period A2 (period during which the backlight 3 is turned off) from the time ta to the time tb. Period A1 and period A2 have the same length. The readout from the first sensor pixel circuit 9a and the readout from the second sensor pixel circuit 9b are performed line-sequentially in parallel after time tc. In addition, in FIG. 3 , the reading from the sensor pixel circuit 9 is completed within one frame period, but it only needs to be completed before the second sensor pixel circuit 9 b is reset in the next frame period.

FIG. 4 is a signal waveform diagram of the display panel 2 . As shown in FIG. 4 , the potentials of the gate lines GL1 to GLx sequentially become high once at predetermined times during one frame period. The potentials of the odd-numbered clock lines CLK1 to CLKn−1 become high level once in a period A1 (more specifically, from time tb to just before time tc) in one frame period. The potentials of the even-numbered clock lines CLK2 to CLKn become high once in a period A2 (more specifically, from time ta to just before time tb) in one frame period. The potentials of the odd-numbered reset lines RST1 to RSTn−1 become high once at a predetermined time at the beginning of the period A1 in one frame period. The potentials of the even-numbered reset lines RST2 to RSTn become high once at a predetermined time at the beginning of the period A2 in one frame period. Two readout lines RWS1 to RWSn are paired, and the potentials of the (n/2) pair of readout lines become high level for a predetermined time sequentially after time tc.

FIG. 5 is a diagram showing a schematic configuration of the sensor pixel circuit 9 . As shown in FIG. 5, the first sensor pixel circuit 9a includes one photodiode D1a and one storage node NDa. The photodiode D1a extracts charges corresponding to the amount of incident light (signal+noise) from the storage node NDa while the backlight 3 is on. Like the first sensor pixel circuit 9a, the second sensor pixel circuit 9b includes one photodiode D1b and one storage node NDb. The photodiode D1b extracts charges according to the amount of incident light (noise) from the storage node NDb while the backlight 3 is off. The first sensor pixel circuit 9 a and the second sensor pixel circuit 9 b hold the detected light amount outside a predetermined detection period. A sensor signal corresponding to the amount of light incident during the detection period when the backlight 3 is turned on is read from the first sensor pixel circuit 9 a. A sensor signal corresponding to the amount of light incident during the detection period when the backlight 3 is turned off is read from the second sensor pixel circuit 9b. By obtaining the difference between the output signal of the first sensor pixel circuit 9a and the output signal of the second sensor pixel circuit 9b using the difference circuit included in the source driver circuit 6, the amount of light when the backlight is turned on and when the backlight is turned off can be obtained. The difference in the amount of light at the time.

In addition, the number of sensor pixel circuits 9 provided in the pixel region 4 may be arbitrary. However, it is preferable to connect the first sensor pixel circuit 9 a and the second sensor pixel circuit 9 b to different output lines. For example, in the case where (n×m) sensor pixel circuits 9 are provided in the pixel area 4, it is only necessary to connect n first sensor pixel circuits 9a to each odd-numbered output line OUT1 to OUTm-1, and to connect each even-numbered output line OUT1 to OUTm-1, It is only necessary to connect n second sensor pixel circuits 9 b to the output lines OUT2 to OUTm. In this case, readout from the sensor pixel circuits 9 is performed row by row. Alternatively, the same number (ie, (x×y/3)) of sensor pixel circuits 9 as color pixels may be provided in the pixel region 4 . Alternatively, sensor pixel circuits 9 having a smaller number (for example, a fraction to several tenths of the color pixels) than the color pixels may be provided in the pixel region 4 .

As described above, the display device according to the embodiment of the present invention is a display device in which a plurality of photodiodes (photosensors) are arranged in the pixel region 4, and includes a display panel 2 including a plurality of display pixel circuits 8 and a plurality of sensor pixel circuits. 9; the backlight 3, which lights up once at a predetermined time during one frame period; and the sensor row drive circuit 7 (driver circuit), which outputs the odd-numbered detection period indicating that the backlight is turned on for the sensor pixel circuit 9 Clock signals CLK1 to CLKn-1 (first control signals) and even-numbered clock signals CLK2 to CLKn (second control signals) indicating the detection period when the backlight is off, and perform reset and readout for the sensor pixel circuit 9 . The sensor pixel circuit 9 includes: a first sensor pixel circuit 9a that detects light during the detection period when the backlight is turned on according to the odd-numbered clock signals CLK1 to CLKn-1, and holds the detected light amount otherwise; 2. The sensor pixel circuit 9b detects light during the detection period when the backlight is turned off according to the even-numbered clock signals CLK2 to CLKn, and holds the detected light amount in other cases. The sensor row drive circuit 7 performs readout from the first sensor pixel circuit 9a and readout from the second sensor pixel circuit 9b line-sequentially except for the detection period when the backlight is on and the detection period when the backlight is off.

Therefore, according to the display device of this embodiment, two types of sensor pixel circuits can be used to detect the light intensity when the backlight is on and the light intensity when the backlight is off, and the difference between the two can be obtained outside the sensor pixel circuit. Thus, an input function that does not depend on the light environment can be provided. In addition, compared with the case where one sensor pixel circuit sequentially detects two kinds of light quantities, the number of readouts from the sensor pixel circuit can be reduced, the readout speed can be reduced, and the power consumption of the device can be reduced. In addition, by performing readout from the sensor pixel circuit outside the detection period, the degree of freedom in determining the timing of turning on and off the backlight, and the timing of resetting and reading out the sensor pixel circuit increases.

The sensor row drive circuit 7 resets the first sensor pixel circuit 9 a at the beginning of the detection period when the backlight is turned on, and resets the second sensor pixel circuit 9 b at the beginning of the detection period when the backlight is turned off. In this way, by resetting the sensor pixel circuits at the beginning of each detection period, it is possible to accurately detect the amount of light in each sensor pixel circuit. Also, by collectively performing resets for the same type of sensor pixel circuits, the same type of sensor pixel circuits can detect light in the same period. In addition, the time required for resetting can be shortened, and the degree of freedom in determining read timing can be increased.

In addition, the detection period (A1 shown in FIG. 3 ) when the backlight is turned on is set immediately after the detection period (A2 shown in FIG. 3 ) when the backlight is turned off. In this way, by setting the two types of detection periods close to each other, it is possible to eliminate the deviation between the two types of detection periods, and to prevent the followability to movement input from changing depending on the input direction. Also, by setting the detection period when the backlight is turned on immediately after the detection period when the backlight is turned off, even when using a backlight that takes longer to turn on than to turn off the backlight, the detection period when the backlight is turned on can be detected. During the whole detection period, the backlight source 3 is turned on to improve the detection accuracy. Also, by setting the lengths of the two types of detection periods to be the same, the amount of light when the backlight is turned on and the amount of light when the backlight is turned off can be detected during periods of the same length, and the amount of light when the backlight is turned on and the amount of light when the backlight is turned off can be accurately obtained. The difference in the amount of light.

In addition, the display panel 2 further includes a plurality of output lines OUT1 to OUTm for transmitting output signals of the first and second sensor pixel circuits 9a and 9b, and the first sensor pixel circuit 9a and the second sensor pixel circuit 9b are connected to different output lines. The sensor row drive circuit 7 performs readout from the first sensor pixel circuit 9a and readout from the second sensor pixel circuit 9b in parallel. The source driver circuit 6 includes a differential circuit that obtains the difference between the output signal of the first sensor pixel circuit 9a and the output signal of the second sensor pixel circuit 9b. In this way, by connecting the first and second sensor pixel circuits 9a and 9b to different output lines according to the type and performing readout from the two types of sensor pixel circuits in parallel, the readout speed can be reduced and the power consumption of the device can be reduced. Also, by providing the differential circuit, the difference between the incident light quantity when the backlight is turned on and the incident light quantity when the backlight is turned off can be immediately obtained, and a memory for storing the previously detected light quantity is unnecessary.

Next, details of the sensor pixel circuit 9 included in the display device of this embodiment will be described. In the following description, the sensor pixel circuit is referred to simply as the pixel circuit, and the same name as the signal line is used to identify the signal on the signal line (for example, the signal on the clock line CLKa is called the clock signal CLKa). In the first, second, sixth, and seventh embodiments, the first sensor pixel circuit 9a is connected to the clock line CLKa, the reset line RSTa, the readout line RWSa, the power supply line VDDa, and the output line OUTa. The second sensor pixel circuit 9b is connected to a clock line CLKb, a reset line RSTb, a readout line RWSb, a power supply line VDDb, and an output line OUTb. In these embodiments, the second sensor pixel circuit 9b has the same configuration as the first sensor pixel circuit 9a, and operates in the same manner, so the description of the second sensor pixel circuit 9b is appropriately omitted. In the third to fifth embodiments, the first sensor pixel circuit 9 a and the second sensor pixel circuit 9 b share some constituent elements, and constitute one pixel circuit. The pixel circuits in the third and fourth embodiments are connected to a common reset line RST and readout line RWS, and the pixel circuit in the fifth embodiment is connected to a common reset line RST, readout line RWS, power supply line VDD, and output line OUT. .

(first embodiment)

6 is a circuit diagram of a pixel circuit according to the first embodiment of the present invention. As shown in FIG. 6, the first pixel circuit 10a includes transistors T1a, M1a, a photodiode D1a, and a capacitor C1a. The second pixel circuit 10b includes transistors T1b, M1b, a photodiode D1b, and a capacitor C1b. The transistors T1a, M1a, T1b, and M1b are N-type TFTs (Thin Film Transistor: thin film transistors).

In the first pixel circuit 10a, the anode of the photodiode D1a is connected to the reset line RSTa, and the cathode is connected to the source of the transistor T1a. The gate of the transistor T1a is connected to the clock line CLKa, and the drain is connected to the gate of the transistor M1a. The drain of the transistor M1a is connected to the power supply line VDDa, and the source is connected to the output line OUTa. The capacitor C1a is provided between the gate of the transistor M1a and the readout line RWSa. In the first pixel circuit 10a, the node connected to the gate of the transistor M1a is a storage node that stores charges corresponding to the amount of detected light, and the transistor M1a functions as a readout transistor. The second pixel circuit 10b has the same configuration as the first pixel circuit 10a.

FIG. 7 is a diagram showing the operation of the first pixel circuit 10a. As shown in FIG. 7 , the first pixel circuit 10 a performs (a) reset, (b) storage, (c) hold, and (d) readout in one frame period.

FIG. 8 is a signal waveform diagram of the first pixel circuit 10a and the second pixel circuit 10b. In FIG. 8, BL represents the brightness of the backlight 3, Vinta represents the potential of the storage node of the first pixel circuit 10a (gate potential of the transistor M1a), and Vintb represents the potential of the storage node of the second pixel circuit 10b (gate potential of the transistor M1b). gate potential). For the first pixel circuit 10a, time t4 to time t5 is a reset period, time t5 to time t6 is a storage period, time t6 to time t7 is a hold period, and time t7 to time t8 is a readout period. For the second pixel circuit 10b, time t1 to time t2 is a reset period, time t2 to time t3 is a storage period, time t3 to time t7 is a hold period, and time t7 to time t8 is a readout period.

In the reset period of the first pixel circuit 10a, the clock signal CLKa is at a high level, the readout signal RWSa is at a low level, and the reset signal RSTa is at a high level for reset. At this time, the transistor T1a is turned on. Therefore, a current (forward current of photodiode D1a) flows from reset line RSTa to the storage node via photodiode D1a and transistor T1a ( FIG. 7( a )), and potential Vinta is reset to a predetermined level.

In the storage period of the first pixel circuit 10a, the clock signal CLKa is at a high level, and the reset signal RSTa and the readout signal RWSa are at a low level. At this time, the transistor T1a is turned on. At this time, when light is incident on the photodiode D1a, a current (photocurrent of the photodiode D1a) flows from the storage node through the reset line RSTa via the transistor T1a and the photodiode D1a, and charge is extracted from the storage node (FIG. 7(b)). Therefore, the potential Vinta falls according to the amount of light incident during the period in which the clock signal CLKa is at the high level (the period during which the backlight 3 is turned on).

During the holding period of the first pixel circuit 10a, the clock signal CLKa, the reset signal RSTa, and the readout signal RWSa are at low level. At this time, the transistor T1a is turned off. At this time, even if light is incident on the photodiode D1a, the transistor T1a is turned off, and the gate of the photodiode D1a and the transistor M1 is electrically disconnected, so the potential Vinta does not change ( FIG. 7( c )).

In the readout period of the first pixel circuit 10a, the clock signal CLKa and the reset signal RSTa are at a low level, and the readout signal RWSa is at a high level for readout. At this time, the transistor T1a is turned off. At this time, the potential Vinta rises by (Cqa/Cpa) times the potential rise of the read signal RWSa (here, Cpa is the capacitance value of the entire first pixel circuit 10a, and Cqa is the capacitance value of the capacitor C1a). Transistor M1a constitutes a source follower amplifier circuit with a transistor (not shown) included in source driver circuit 6 as a load, and drives output line OUTa according to potential Vinta ( FIG. 7( d )).

The second pixel circuit 10b operates in the same manner as the first pixel circuit 10a. The potential Vintb is reset to a predetermined level during the reset period, falls with the amount of light incident during the period when the clock signal CLKb is at a high level (the period when the backlight 3 is turned off) during the storage period, and does not change during the hold period. During the readout period, the potential Vintb rises by (Cqb/Cpb) times (Cqb/Cpb) (here, Cpb is the capacitance value of the entire second pixel circuit 10b, and Cqb is the capacitance value of the capacitor C1b) of the rise amount of the potential of the readout signal RWSb. M1b drives the output line OUTb according to the potential Vintb.

As described above, the first pixel circuit 10a of the present embodiment includes: one photodiode D1a (photosensor); one storage node that stores charges corresponding to the amount of light detected; and a transistor M1a (readout transistor) that It has a control terminal connected to the storage node, and a transistor T1a (switching element for holding) provided on a path of a current flowing through the photodiode D1a, and turned on/off according to the clock signal CLK. The transistor T1a is provided between the storage node and one end of the photodiode D1a, and the other end of the photodiode D1a is connected to the reset line RSTa. The transistor T1a is turned on during the detection period when the backlight is turned on according to the clock signal CLKa. The second pixel circuit 10b has the same configuration as the first pixel circuit 10a, and the transistor T1b included in the second pixel circuit 10b is turned on during the detection period when the backlight is turned off.

In this way, by providing the transistor T1a turned on during the detection period when the backlight is turned on on the path of the current flowing through the photodiode D1a, the detection period when the backlight is turned off is provided on the path of the current flowing through the photodiode D1b. The turned-on transistor T1b can constitute: the first pixel circuit 10a, which detects light during the detection period when the backlight is turned on, and maintains the detected light amount otherwise; and the second pixel circuit 10b, which is turned off when the backlight is turned off. Light is detected during the detection period of the hour, and the amount of light detected is maintained at other times.

(second embodiment)

9 is a circuit diagram of a pixel circuit according to a second embodiment of the present invention. As shown in FIG. 9, the first pixel circuit 20a includes transistors T1a, T2a, and M1a, a photodiode D1a, and a capacitor C1a. The second pixel circuit 20b includes transistors T1b, T2b, and M1b, a photodiode D1b, and a capacitor C1b. The transistors T1a, T2a, M1a, T1b, T2b, and M1b are N-type TFTs.

In the first pixel circuit 20a, the gates of the transistors T1a and T2a are connected to the clock line CLKa. The source of the transistor T2a is connected to the reset line RSTa, and the drain is connected to the anode of the photodiode D1a. The cathode of photodiode D1a is connected to the source of transistor T1a. The drain of transistor T1a is connected to the gate of transistor M1a. The drain of the transistor M1a is connected to the power supply line VDDa, and the source is connected to the output line OUTa. The capacitor C1a is provided between the gate of the transistor M1a and the readout line RWSa. In the first pixel circuit 20a, the node connected to the gate of the transistor M1a is a storage node, and the transistor M1a functions as a readout transistor. The second pixel circuit 20b has the same configuration as the first pixel circuit 20a.

FIG. 10 is a diagram showing the operation of the first pixel circuit 20a. As shown in FIG. 10 , the first pixel circuit 20 a performs (a) reset, (b) storage, (c) hold, and (d) readout in one frame period. The signal waveform diagrams of the first and second pixel circuits 20a and 20b are the same as those of the first embodiment (FIG. 8). The first pixel circuit 20a operates in the same manner as the first pixel circuit 10a of the first embodiment except that the transistor T2a is turned on/off at the same timing as the transistor T1a. The same applies to the second pixel circuit 20b.

As described above, the first pixel circuit 20a of the present embodiment includes: one photodiode D1a (photosensor); one storage node that stores charges corresponding to the amount of light detected; and a transistor M1a (readout transistor) that It has a control terminal connected to a storage node; and transistors T1a, T2a (two holding switching elements). The transistor T1a is provided between the storage node and one end of the photodiode D1a, and the transistor T2a is provided between the reset line RSTa and the other end of the photodiode D1a. The transistors T1a and T2a are turned on during the detection period when the backlight is turned on according to the clock signal CLKa. The second pixel circuit 20b has the same configuration as the first pixel circuit 20a, and the transistors T1b and T2b included in the second pixel circuit 20b are turned on during the detection period when the backlight is turned off.

In this way, transistors T1a, T2a that are turned on during the detection period when the backlight is turned on are provided on both sides of the photodiode D1a, and transistors T1b, T2a that are turned on during the detection period when the backlight is turned off are provided on both sides of the photodiode D1b. T2b can constitute: the first pixel circuit 20a, which detects light during the detection period when the backlight is turned on, and maintains the amount of light detected otherwise; and the second pixel circuit 20b, which detects the light when the backlight is turned off. Detects light, otherwise maintains the amount of light detected.

In addition, in the first pixel circuit 20a, the transistor T2a provided between the photodiode D1a and the reset line RSTa is turned off except for the detection period when the backlight is turned on. Therefore, the variation in the potential of the cathode of the photodiode D1a due to the current flowing through the photodiode D1a becomes smaller, and the potential difference applied to both ends of the transistor T1a becomes smaller. This reduces the leakage current flowing through the transistor T1a, prevents fluctuations in the potential of the storage node, and improves detection accuracy. The same effect is also obtained in the second pixel circuit 20b.

(third embodiment)

11 is a circuit diagram of a pixel circuit according to a third embodiment of the present invention. The pixel circuit 30 shown in FIG. 11 includes transistors T1a, T1b, M1a, M1b, a photodiode D1, and capacitors C1a, C1b. Transistors T1a, T1b, M1a, and M1b are N-type TFTs. In FIG. 11 , the left half corresponds to the first pixel circuit, and the right half corresponds to the second pixel circuit. The pixel circuit 30 is connected to clock lines CLKa, CLKb, reset line RST, readout line RWS, power supply lines VDDa, VDDb, and output lines OUTa, OUTb.

As shown in FIG. 11, the anode of the photodiode D1 is connected to the reset line RST, and the cathode is connected to the sources of the transistors T1a, T1b. The gate of the transistor T1a is connected to the clock line CLKa, and the drain is connected to the gate of the transistor M1a. The drain of the transistor M1a is connected to the power supply line VDDa, and the source is connected to the output line OUTa. The capacitor C1a is provided between the gate of the transistor M1a and the readout line RWS. The gate of the transistor T1b is connected to the clock line CLKb, and the drain is connected to the gate of the transistor M1b. The drain of the transistor M1b is connected to the power supply line VDDb, and the source is connected to the output line OUTb. The capacitor C1b is provided between the gate of the transistor M1b and the readout line RWS. In the pixel circuit 30, the node connected to the gate of the transistor M1a is the first storage node, the node connected to the gate of the transistor M1b is the second storage node, and the transistors M1a and M1b function as readout transistors.

FIG. 12 is a diagram showing the operation of the pixel circuit 30 . As shown in FIG. 12 , the pixel circuit 30 performs (a) reset when the backlight is off, (b) storage when the backlight is off, (c) reset when the backlight is on, and (d) Store when lit, (e) hold, and (f) read.

FIG. 13 is a signal waveform diagram of the pixel circuit 30 . In FIG. 13, Vinta represents the potential of the first storage node (the gate potential of the transistor M1a), and Vintb represents the potential of the second storage node (the gate potential of the transistor M1b). In Figure 13, time t1 to time t2 is the reset period when the backlight is off, time t2 to time t3 is the storage period when the backlight is off, time t4 to time t5 is the reset period when the backlight is on, and time t5 Time t6 to time t6 is a storage period when the backlight is turned on, time t3 to time t4 and time t6 to time t7 are hold periods, and time t7 to time t8 is a readout period.

During the reset period when the backlight is turned off, the clock signal CLKb is at a high level, the clock signal CLKa and the readout signal RWS are at a low level, and the reset signal RST is at a high level for reset. At this time, the transistor T1a is turned off, and the transistor T1b is turned on. Therefore, a current (forward current of the photodiode D1 ) flows from the reset line RST to the second storage node ( FIG. 12( a )) via the photodiode D1 and the transistor T1b, and the potential Vintb is reset to a predetermined level.

During the storage period when the backlight is turned off, the clock signal CLKb is at a high level, and the clock signal CLKa, the reset signal RST, and the readout signal RWS are at a low level. At this time, the transistor T1a is turned off, and the transistor T1b is turned on. At this time, when light is incident on the photodiode D1, a current (photocurrent of the photodiode D1) flows from the second storage node to the reset line RST via the transistor T1b and the photodiode D1, and charges are extracted from the second storage node (FIG. 12( b)). Therefore, the potential Vintb falls according to the amount of light incident during this period (turn-off time of the backlight 3). Also, during this period, the potential Vinta does not change.

During the reset period when the backlight is turned on, the clock signal CLKa is at a high level, the clock signal CLKb and the readout signal RWS are at a low level, and the reset signal RST is at a high level for reset. At this time, the transistor T1a is turned on, and the transistor T1b is turned off. Therefore, a current (forward current of photodiode D1 ) flows from reset line RST to the first storage node via photodiode D1 and transistor T1 a ( FIG. 12( c )), and potential Vinta is reset to a predetermined level.

During the storage period when the backlight is turned on, the clock signal CLKa is at high level, and the clock signal CLKb, reset signal RST, and readout signal RWS are at low level. At this time, the transistor T1a is turned on, and the transistor T1b is turned off. At this time, when light is incident on the photodiode D1, a current (photocurrent of the photodiode D1) flows from the first storage node to the reset line RST via the transistor T1a and the photodiode D1, and charges are extracted from the first storage node (FIG. 12( d)). Therefore, the potential Vinta falls according to the amount of light incident during this period (lighting time of the backlight 3 ). Also, during this period, the potential Vintb does not change.

During the hold period, the clock signals CLKa, CLKb, the reset signal RST, and the read signal RWS are at low level. At this time, the transistors T1a, T1b are turned off. At this time, even if light enters the photodiode D1, the transistors T1a and T1b are turned off, and the gates of the photodiode D1 and the transistors M1a and M1b are electrically cut off, so the potentials Vinta and Vintb do not change ( FIG. 12( e )).

In the read period, clock signals CLKa, CLKb and reset signal RST are at low level, and read signal RWS is at high level for read. At this time, the transistors T1a and T1b are turned off. At this time, the potentials Vinta and Vintb rise to the extent that the potential of the read signal RWS rises, and a current Ia corresponding to the potential Vinta flows between the drain and the source of the transistor M1a, and flows between the drain and the source of the transistor M1b. A current Ib of an amount corresponding to the potential Vintb flows (FIG. 12(f)). The current Ia is input to the source drive circuit 6 via the output line OUTa, and the current Ib is input to the source drive circuit 6 via the output line OUTb.

As described above, the pixel circuit 30 of the present embodiment has a configuration in which one photodiode D1 (photosensor) is shared between the first and second pixel circuits 10 a and 10 b of the first embodiment. The cathode of the common photodiode D1 is connected to the source of the transistor T1a included in the part corresponding to the first pixel circuit and the source of the transistor T1b included in the part corresponding to the second pixel circuit.

According to the pixel circuit 30, similarly to the first and second pixel circuits 10a and 10b of the first embodiment, it is possible to detect the amount of light when the backlight is turned on and the amount of light when the backlight is turned off. In addition, by sharing one photodiode D1 between the two types of pixel circuits, the influence of dispersion in the sensitivity characteristics of the photodiode can be eliminated, and the difference between the light quantity when the backlight is turned on and the light quantity when the backlight is turned off can be accurately obtained. In addition, the number of photodiodes can be reduced, the aperture ratio can be increased, and the sensitivity of the sensor pixel circuit can be improved.

(fourth embodiment)

14 is a circuit diagram of a pixel circuit according to a fourth embodiment of the present invention. The pixel circuit 40 shown in FIG. 14 includes transistors T1a, T1b, T2a, T2a, M1a, M1b, a photodiode D1, and capacitors C1a, C1b. The transistors T1a, T1b, T2a, T2b, M1a, and M1b are N-type TFTs. In FIG. 14 , the left half corresponds to the first pixel circuit, and the right half corresponds to the second pixel circuit. The pixel circuit 40 is connected to clock lines CLKa, CLKb, reset line RST, readout line RWS, power supply lines VDDa, VDDb, and output lines OUTa, OUTb.

As shown in FIG. 14, the gates of the transistors T1a, T2a are connected to the clock line CLKa, and the gates of the transistors T2a, T2b are connected to the clock line CLKb. The sources of the transistors T2a and T2b are connected to the reset line RST, and the drains are connected to the anode of the photodiode D1. The cathode of photodiode D1 is connected to the sources of transistors T1a, T1b. The gate of the transistor T1a is connected to the clock line CLKa, and the drain is connected to the gate of the transistor M1a. The drain of the transistor M1a is connected to the power supply line VDDa, and the source is connected to the output line OUTa. The capacitor C1a is provided between the gate of the transistor M1a and the readout line RWS. The gate of the transistor T1b is connected to the clock line CLKb, and the drain is connected to the gate of the transistor M1b. The drain of the transistor M1b is connected to the power supply line VDDb, and the source is connected to the output line OUTb. The capacitor C1b is provided between the gate of the transistor M1b and the readout line RWS. In the pixel circuit 40, the node connected to the gate of the transistor M1a is the first storage node, the node connected to the gate of the transistor M1b is the second storage node, and the transistors M1a and M1b function as readout transistors.

FIG. 15 is a diagram showing the operation of the pixel circuit 40 . As shown in FIG. 15 , the pixel circuit 40 performs (a) reset when the backlight is off, (b) storage when the backlight is off, (c) reset when the backlight is on, and (d) Store when lit, (e) hold, and (f) read. The signal waveform diagram of the pixel circuit 40 is the same as that of the third embodiment ( FIG. 13 ). The pixel circuit 40 operates in the same manner as the pixel circuit 30 of the third embodiment, except that the transistors T2a, T2b are turned on/off at the same timing as the transistors T1a, T2a, respectively.

As described above, the pixel circuit 40 of the present embodiment has a configuration in which one photodiode D1 (photosensor) is shared between the first and second pixel circuits 20 a and 20 b of the second embodiment. The cathode of the common photodiode D1 is connected to the source of the transistor T1a included in the part corresponding to the first pixel circuit and the source of the transistor T1b included in the part corresponding to the second pixel circuit. The anode of the photodiode D1 is connected to the drain of the transistor T2a included in the part corresponding to the first pixel circuit and the drain of the transistor T2b included in the part corresponding to the second sensor pixel circuit.

According to the pixel circuit 40, similarly to the first and second pixel circuits 20a and 20b of the second embodiment, it is possible to detect the amount of light when the backlight is turned on and the amount of light when the backlight is turned off. In addition, similarly to the second embodiment, the leakage current flowing through the transistors T1a and T1b can be reduced, the potential fluctuations of the first and second storage nodes can be prevented, and detection accuracy can be improved. In addition, by sharing one photodiode D1 between the two types of pixel circuits, the influence of dispersion in the sensitivity characteristics of the photodiode can be eliminated, and the difference between the light quantity when the backlight is turned on and the light quantity when the backlight is turned off can be accurately obtained. In addition, the number of photodiodes can be reduced, the aperture ratio can be increased, and the sensitivity of the sensor pixel circuit can be improved.

(fifth embodiment)

16 is a circuit diagram of a pixel circuit according to a fifth embodiment of the present invention. The pixel circuit 50 shown in FIG. 16 includes transistors T1a, T1b, M1, a photodiode D1, and capacitors C1a, C1b. Transistors T1a, T1b, and M1 are N-type TFTs. In FIG. 16 , the left half corresponds to the first pixel circuit, and the right half corresponds to the second pixel circuit. The pixel circuit 50 is connected to clock lines CLKa, CLKb, reset line RST, readout line RWS, power supply line VDD, and output line OUT.

As shown in FIG. 16, the anode of the photodiode D1 is connected to the reset line RST, and the cathode is connected to the sources of the transistors T1a, T1b and the gate of the transistor M1. The gate of the transistor T1a is connected to the clock line CLKa, and the gate of the transistor T1b is connected to the clock line CLKb. The capacitor C1a is provided between the drain of the transistor T1a and the readout line RWS. The capacitor C1b is provided between the drain of the transistor T1b and the readout line RWS. The drain of the transistor M1 is connected to the power supply line VDD, and the source is connected to the output line OUT. In the pixel circuit 50, the node connected to the drain of the transistor T1a is the first storage node, the node connected to the drain of the transistor T1b is the second storage node, and the transistor M1 functions as a readout transistor.

FIG. 17 is a diagram showing the operation of the pixel circuit 50 . As shown in FIG. 17 , the pixel circuit 50 performs (a) reset when the backlight is off, (b) storage when the backlight is off, (c) reset when the backlight is on, and (d) Store at the time of lighting, (e) hold, (f) initialize immediately before reading, (g) read out the amount of light when the backlight is off, and (h) read out the amount of light when the backlight is on. The initialization just before reading is performed twice in total before reading the light intensity when the backlight is turned off and before reading the light intensity when the backlight is turned on.

FIG. 18 is a signal waveform diagram of the pixel circuit 50 . In FIG. 18, Vinta represents the potential of the first storage node (the drain potential of the transistor T1a), and Vintb represents the potential of the second storage node (the drain potential of the transistor T1b). In Figure 18, time t1 to time t2 is the reset period when the backlight is off, time t2 to time t3 is the storage period when the backlight is off, time t4 to time t5 is the reset period when the backlight is on, and time t5 Time t6 to time t6 is the storage period when the backlight is turned on, time t3 to time t4 and time t6 to time t7 are the hold periods, time t7 to time t8 and time t11 to time t12 are the initialization periods immediately before reading, and time t9 From time t10 to time t10 is a period for reading out the amount of light when the backlight is turned off, and from time t13 to time t14 is a period for reading out the amount of light when the backlight is turned on.

In the reset period when the backlight is turned off, the storage period when the backlight is turned off, the reset period when the backlight is turned on, the storage period and the hold period when the backlight is turned on, the pixel circuit 50 and the pixel circuit 30 of the third embodiment The operation is performed in the same manner (Fig. 17(a) to (e)).

In the initializing period immediately before reading, clock signals CLKa, CLKb and read signal RWS are at low level, and reset signal RST is at high level for reset. At this time, the transistors T1a, T1b are turned off. Therefore, a current (forward current of photodiode D1 ) flows from reset line RST via photodiode D1 to node N1 connected to the cathode of photodiode D1 ( FIG. 17( f )), and the potential of node N1 is reset to a predetermined level.

During the reading period when the backlight is turned off, the clock signal CLKb is at a high level, the clock signal CLKa and the reset signal RST are at a low level, and the read signal RWS is at a high level for reading. At this time, the transistor T1a is turned off, and the transistor T1b is turned on. At this time, the potential Vintb rises by (Cqb/Cpb) times (Cqb/Cpb) (here, Cpb is the capacitance value of the part corresponding to the second pixel circuit, and Cqb is the capacitance value of the capacitor C1b) of the rise amount of the potential of the read signal RWS, and the transistor M1b The output line OUT is driven according to the potential Vintb (FIG. 17(g)).

During the reading period of the light intensity of the backlight, the clock signal CLKa is at high level, the clock signal CLKb and the reset signal RST are at low level, and the readout signal RWS is at high level for reading. At this time, the transistor T1a is turned on, and the transistor T1b is turned off. At this time, the potential Vinta rises by (Cqa/Cpa) times the potential rise of the read signal RWS (here, Cpa is the capacitance value of the part corresponding to the first pixel circuit, and Cqa is the capacitance value of the capacitor C1a), and the transistor M1a drives the output line OUT according to the potential Vinta (FIG. 17(h)).

As described above, the pixel circuit 50 of the present embodiment has a configuration in which the photodiode D1 and the transistor M1 (readout transistor) are shared between the first and second pixel circuits 10a and 10b of the first embodiment. The gate (control terminal) of the common transistor M1 is connected to one end of the common photodiode D1, one end of the transistor T1a included in the part corresponding to the first pixel circuit, and a transistor included in the part corresponding to the second pixel circuit. One end of T1b. In this way, the gate of transistor M1 is configured to be electrically connected to the first and second storage nodes via transistors T1a and T1b.

According to the pixel circuit 50 , similarly to the pixel circuit 30 of the third embodiment, it is possible to detect the amount of light when the backlight is turned on and the amount of light when the backlight is turned off. In addition, by sharing one photodiode D1 between two types of pixel circuits, the same effect as that of the third embodiment can be obtained. In addition, by sharing the transistor M1 between the two types of pixel circuits, the influence of variation in the threshold characteristic of the transistor M1 can be eliminated, and the difference between the light quantity when the backlight is turned on and the light quantity when the backlight is turned off can be accurately obtained.

(sixth embodiment)

19 is a circuit diagram of a pixel circuit according to a sixth embodiment of the present invention. As shown in FIG. 19, the first pixel circuit 60a includes transistors T1a, M1a, a photodiode D1a, and a capacitor C1a. The second pixel circuit 60b includes transistors T1b and M1b, a photodiode D1b, and a capacitor C1b. Transistors T1a, M1a, T1b, and M1b are N-type TFTs.

In the first pixel circuit 60a, the source of the transistor T1a is connected to the reset line RSTa, the gate is connected to the clock line CLKa, and the drain is connected to the anode of the photodiode D1a. The cathode of photodiode D1a is connected to the gate of transistor M1a. The drain of the transistor M1a is connected to the power supply line VDDa, and the source is connected to the output line OUTa. The capacitor C1a is provided between the gate of the transistor M1a and the readout line RWSa. In the first pixel circuit 60a, the node connected to the gate of the transistor M1a is a storage node, and the transistor M1a functions as a readout transistor. The second pixel circuit 60b has the same configuration as that of the first pixel circuit 60a.

The first and second pixel circuits 60a and 60b operate in the same manner as the first and second pixel circuits 10a and 10b of the first embodiment (see FIG. 7 ). The signal waveform diagrams of the first and second pixel circuits 60a and 60b are the same as those of the first embodiment (FIG. 8).

As described above, the first pixel circuit 60 a of the present embodiment includes the same constituent elements as the first pixel circuit 10 a of the first embodiment. However, in the first pixel circuit 60a, the photodiode D1a is provided between the storage node and one end of the transistor T1a, and the other end of the transistor T1a is connected to the reset line RSTa. The transistor T1a is turned on during the detection period when the backlight is turned on according to the clock signal CLKa. The second pixel circuit 60b has the same configuration as the first pixel circuit 60a, and the transistor T1b included in the second pixel circuit 60b is turned on during the detection period when the backlight is turned off.

In this way, by providing the transistor T1a turned on during the detection period when the backlight is turned on on the path of the current flowing through the photodiode D1a, the detection period when the backlight is turned off is provided on the path of the current flowing through the photodiode D1b. The turned-on transistor T1b can constitute: the first pixel circuit 60a, which detects light during the detection period when the backlight is turned on, and maintains the detected light amount otherwise; and the second pixel circuit 60b, which turns off the backlight. Light is detected during the detection period of the hour, and the amount of light detected is maintained at other times.

(seventh embodiment)

20 is a circuit diagram of a pixel circuit according to a seventh embodiment of the present invention. As shown in FIG. 20, the first pixel circuit 70a includes transistors T1a, T2a, T3a, and M1a, a photodiode D1a, and a capacitor C1a. The second pixel circuit 70b includes transistors T1b, T2b, T3b, and M1b, a photodiode D1b, and a capacitor C1b. The transistors T1a, T3a, M1a, T1b, T3b, and M1b are N-type TFTs, and the transistors T2a, T2b are P-type TFTs. A high-level potential VDDP is supplied to the first pixel circuit 70a and the second pixel circuit 70b.

In the first pixel circuit 70a, the gates of the transistors T1a and T2a are connected to the clock line CLKa. The source of the transistor T1a is connected to the reset line RSTa, and the drain is connected to the anode of the photodiode D1a and the drain of the transistor T2a. The cathode of photodiode D1a is connected to the gate of transistor M1a. The drain of the transistor M1a is connected to the power supply line VDDa, and the source is connected to the output line OUTa. The capacitor C1a is provided between the gate of the transistor M1a and the readout line RWSa. The drain of transistor T3a is applied with potential VDDP, the gate is connected to the gate of transistor M1a, and the source is connected to the source of transistor T2a. In the first pixel circuit 70a, the node connected to the gate of the transistor M1a is a storage node, and the transistor M1a functions as a readout transistor. The second pixel circuit 70b has the same configuration as that of the first pixel circuit 70a.

The first and second pixel circuits 70a and 70b operate in the same manner as the first and second pixel circuits 60a and 60b of the sixth embodiment except for the following. The transistor T2a is turned off when the clock signal CLKa is at a high level, and is turned on when the clock signal CLKa is at a low level. The transistor T2b is turned off when the clock signal CLKb is at a high level, and is turned on when the clock signal CLKb is at a low level.

When the clock signal CLKa changes from high level to low level at the end of the detection period when the backlight is turned on, the transistor T2a is turned from off to on. The node connected to the anode of the photodiode D1a at this instant is charged at a potential corresponding to the gate potential Vinta of the transistor M1a through the transistors T2a and T3a. Therefore, at the end of the detection period when the backlight is turned on, the current flowing through the photodiode D1a is cut off immediately.

Also, when the clock signal CLKb changes from high level to low level at the end of the detection period when the backlight is turned off, the transistor T2b is turned from off to on. The node connected to the anode of the photodiode D1b at this instant is charged at a potential corresponding to the gate potential Vintb of the transistor M1b via the transistors T2b and T3b. Therefore, at the end of the detection period when the backlight is turned off, the current flowing through the photodiode D1b is cut off immediately.

As described above, the first pixel circuit 70a of the present embodiment is a circuit in which the following circuit is added to the first pixel circuit 60a of the sixth embodiment: the transistor T2a (first switching element), one end of which is connected to the anode of the photodiode D1a ( The terminal on the side of the transistor T1a) is turned on/off according to the clock signal CLKa; and the transistor T3a (second switching element) applies a potential corresponding to the potential of the storage node to the source of the transistor T2a. The transistor T2a is turned on when the clock signal CLKa is at low level (except for the detection period when the backlight is turned on). The second pixel circuit 10b has the same configuration as the first pixel circuit 10a, and the transistor T2b included in the second pixel circuit 70b is turned on when the clock signal CLKb is at low level (except for the detection period when the backlight is turned off).

According to the first and second pixel circuits 70a and 70b, similarly to the first and second pixel circuits 60a and 60b of the sixth embodiment, it is possible to detect the amount of light when the backlight is on and the amount of light when the backlight is off. Also, by applying a potential corresponding to the potential of the storage node to the terminal of the photodiode D1a opposite to the storage node when the clock signal CLKa changes, the current flowing through the photodiode D1a can be immediately cut off, thereby improving detection accuracy. The same effect is also obtained in the second pixel circuit 70b.

(modified example of embodiment)

Each embodiment of the present invention can constitute modified examples shown below. 21A to 21H are circuit diagrams of pixel circuits in first to eighth modifications of the first embodiment, respectively. The first pixel circuits 11 a to 18 a shown in FIGS. 21A to 21H are obtained by modifying the first pixel circuit 10 a of the first embodiment as follows. The second pixel circuits 11b to 18b are obtained by modifying the second pixel circuit 10b of the first embodiment similarly.

The first pixel circuit 11a shown in FIG. 21A is a circuit in which the capacitor C1 included in the first pixel circuit 10a is replaced with a transistor TCa which is a P-type TFT. In the first pixel circuit 11a, the drain of the transistor TCa is connected to the drain of the transistor T1a, the source is connected to the gate of the transistor M1a, and the gate is connected to the readout line RWSa. Transistor TCa connected in this way changes the potential of the storage node more than that of the original pixel circuit when a high level for readout is applied to readout line RWSa. Therefore, the difference between the potential of the storage node when strong light is incident and the potential of the storage node when weak light is incident can be amplified, and the sensitivity of the pixel circuit 11 a can be improved.

The first pixel circuit 12a shown in FIG. 21B is a circuit in which the photodiode D1 included in the first pixel circuit 10a is replaced with a phototransistor TDa. Thus, all transistors included in the first pixel circuit 12a are N-type. Therefore, the first pixel circuit 12a can be manufactured using a single-channel process capable of manufacturing only N-type transistors.

The first pixel circuit 13a shown in FIG. 21C is a circuit in which the photodiode D1a included in the first pixel circuit 10a is reversely connected. The first pixel circuit 13a is supplied with a reset signal RSTa which is normally at a high level and is at a low level for resetting at the time of resetting. The cathode of the photodiode D1a is connected to the reset line RSTa, and the anode is connected to the drain of the transistor T1a. Thus, deformation of the pixel circuit is obtained.

The first pixel circuit 14a shown in FIG. 21D is a circuit in which the photodiode D1a included in the first pixel circuit 10a is reversely connected, and the capacitor C1a is deleted. The same reset signal RSTa as that of the first pixel circuit 13a is supplied to the first pixel circuit 14a. However, the reset signal RSTa is at a high level for reading during reading. When the reset signal RSTa is at a high level for reading, the potential of the storage node (the gate potential of the transistor M1a) rises, and a current corresponding to the potential of the storage node flows through the transistor M1a. Thus, the first pixel circuit 14a does not include the capacitor C1a. Therefore, the aperture ratio can be increased by the level of the capacitor C1a, and the sensitivity of the pixel circuit can be improved.

The first pixel circuit 15a shown in FIG. 21E is a circuit in which a transistor TSa is added to the first pixel circuit 10a. The transistor TSa is an N-type TFT, and functions as a switching element for selection. In the first pixel circuit 15a, the source of the transistor M1a is connected to the drain of the transistor TSa. The source of the transistor TSa is connected to the output line OUTa, and the gate is connected to the selection line SELa. The selection signal SELa is at a high level when reading from the first pixel circuit 15a. Thus, deformation of the pixel circuit is obtained.

The first pixel circuit 16a shown in FIG. 21F is a circuit in which a transistor TRa is added to the first pixel circuit 10a. The transistor TRa is an N-type TFT, and functions as a reset switching element. In the first pixel circuit 16a, the low-level potential VSS is applied to the source of the transistor TRa, the drain is connected to the gate of the transistor M1a, and the gate is connected to the reset line RSTa. In addition, a low-level potential COM is applied to the anode of the photodiode D1a. Thus, deformation of the pixel circuit is obtained.

The first pixel circuit 17a shown in FIG. 21G is a circuit in which the above-mentioned transistors TSa and TRa are added to the first pixel circuit 10a. The connection form of the transistors TSa, TRa is the same as that of the first pixel circuits 15a, 16a. Thus, deformation of the pixel circuit is obtained.

The first pixel circuit 18a shown in FIG. 21H is a circuit in which a photodiode D2a is added to the first pixel circuit 10a. The photodiode D2a is shielded from light and functions as a reference light sensor. The anode of the photodiode D2a is connected to the cathode of the photodiode D1a and the source of the transistor T1a, and a predetermined potential VC is applied to the cathode. The potential VC is higher than the high-level potential for resetting. Since a dark current flows through the photodiode D2a, temperature compensation of the photodiode can be performed.

The second to seventh embodiments can also be modified in the same way. In addition, in the first to seventh embodiments, as long as the properties of the above-mentioned deformations are not violated, the above-mentioned deformations can be combined arbitrarily to constitute various modification examples.

As described above, in the display device according to the embodiment of the present invention and its modifications, the first sensor pixel circuit and the second sensor pixel circuit that detect light during a predetermined detection period and hold the detected light amount otherwise are in the pixel Multiple regions are configured. The backlight is turned on once at a predetermined time in one frame period, and a detection period when the backlight is turned on and a detection period when the backlight is turned off are set once in each frame period. The first sensor pixel circuit is reset at the beginning of a detection period when the backlight is turned on, and detects light during the detection period. The second sensor pixel circuit is reset at the beginning of a detection period when the backlight is turned off, and detects light during this detection period. Readout from the pixel circuits of the two types of sensors is performed line-sequentially in parallel except for the two types of detection periods. A difference circuit provided outside the sensor pixel circuit calculates the difference between the light quantity when the backlight is turned on and the light quantity when the backlight is turned off. Thereby, the conventional problem can be solved, and the input function which does not depend on the light environment can be provided.

In addition, in the present invention, the type of light source provided in the display device is not particularly limited. Therefore, for example, a visible light backlight provided for display can be turned on once at a predetermined time in one frame period. Alternatively, an infrared light backlight for photodetection may be provided in the display device separately from a visible light backlight for display. In such a display device, the visible light backlight can be turned on all the time, and only the infrared light backlight can be turned on once at a predetermined time in one frame period.

In addition, the backlight may be turned on multiple times for a predetermined time during one frame period. In this case, the detection period when the backlight is turned on may be set covering a plurality of periods when the backlight is turned on, and the detection period when the backlight is turned off may be set for other periods. Also in this case, it is preferable that the detection period when the backlight is turned on and the detection period when the backlight is turned off are set to have the same length. Also, the detection period when the backlight is turned off may be set immediately after the detection period when the backlight is turned on. This eliminates the difference between the two types of detection periods, prevents followability to movement input from changing depending on the input direction, and suppresses detection errors caused by light leakage in switching elements included in the sensor pixel circuit.

Industrial availability

The display device of the present invention is characterized by having an input function independent of the light environment, and thus can be used in various display devices in which a plurality of photosensors are provided on a display panel.

Explanation of reference signs

1: display control circuit

2: Display panel

3: Backlight

4: Pixel area

5: Gate drive circuit

6: Source drive circuit

7: Sensor row drive circuit

8: Display pixel circuit

9: Sensor pixel circuit

10～18, 20, 30, 40, 50, 60, 70: pixel circuit

Claims (15)

1. a display device is characterized in that,

Dispose a plurality of optical sensors in the viewing area,

Possess:

Display panel, it comprises a plurality of display pixel circuits and a plurality of sensor pixel circuit;

Light source, it was lighted with the stipulated time in 1 image duration

Driving circuit, the 2nd control signal during the detection when the 1st control signal during its detection during to the sensor image element circuit output expression light source igniting is extinguished with the expression light source, and be directed against resetting and reading of the sensor image element circuit,

The sensor image element circuit comprises:

The 1st sensor pixel circuit, it surveys light according to above-mentioned the 1st control signal during detection when light source igniting, keeps the light quantity that detects in the time of in addition; And

The 2nd sensor pixel circuit, it surveys light according to above-mentioned the 2nd control signal during detection when light source extinguishes, the light quantity that maintenance detects in the time of in addition,

During the detection of above-mentioned driving circuit when light source igniting with the detection of light source when extinguishing during beyond carry out reading by the line order from above-mentioned the 1st sensor pixel circuit and the 2nd sensor pixel circuit.

2. display device according to claim 1 is characterized in that,

Above-mentioned light source was lighted 1 time with the stipulated time in 1 image duration,

Respectively set 1 time in 1 image duration during detection during light source igniting with during the detection of light source when extinguishing.

3. display device according to claim 2; It is characterized in that; Beginning during the detection of above-mentioned driving circuit when light source igniting is directed against resetting of above-mentioned the 1st sensor pixel circuit, and the beginning during the detection when light source extinguishes is directed against resetting of above-mentioned the 2nd sensor pixel circuit.

4. display device according to claim 2 is characterized in that, be set in during the detection during light source igniting during the detection of light source when extinguishing tight after.

5. display device according to claim 2 is characterized in that, during the detection when being set in light source igniting during the detection when light source extinguishes tight after.

6. display device according to claim 2 is characterized in that, is equal length during the detection during light source igniting with during the detection of light source when extinguishing.

7. display device according to claim 1 is characterized in that,

Above-mentioned display panel also comprises many output lines of the output signal of above-mentioned the 1st sensor pixel circuit of transmission and the 2nd sensor pixel circuit,

Above-mentioned the 1st sensor pixel circuit is connected to different output lines with the 2nd sensor pixel circuit by kind,

Above-mentioned driving circuit carries out reading from above-mentioned the 1st sensor pixel circuit and the 2nd sensor pixel circuit concurrently.

8. display device according to claim 7,

Also possess difference channel, above-mentioned difference channel is obtained output signal poor of output signal and above-mentioned the 2nd sensor pixel circuit of above-mentioned the 1st sensor pixel circuit.

9. display device according to claim 1 is characterized in that,

Above-mentioned the 1st sensor pixel circuit and the 2nd sensor pixel circuit comprise:

1 optical sensor;

1 memory node, its storage and the light quantity corresponding charge that detects;

Read transistor, it has the control terminal that can be electrically connected with above-mentioned memory node; And

Keep using on-off element, it is located on the path of current that flows through above-mentioned optical sensor, according to the control signal conduction and cut-off that is endowed,

The maintenance that above-mentioned the 1st sensor pixel circuit is comprised with on-off element according to the detection of above-mentioned the 1st control signal when the light source igniting during conducting, the maintenance that above-mentioned the 2nd sensor pixel circuit is comprised with on-off element according to the detection of above-mentioned the 2nd control signal when light source extinguishes during conducting.

10. display device according to claim 9 is characterized in that,

In above-mentioned the 1st sensor pixel circuit and the 2nd sensor pixel circuit,

Above-mentioned maintenance is located at on-off element between the end of above-mentioned memory node and above-mentioned optical sensor,

The other end of above-mentioned optical sensor is connected to reset line.

11. display device according to claim 9,

Above-mentioned the 1st sensor pixel circuit and the 2nd sensor pixel circuit comprise following element and use on-off element as above-mentioned maintenance:

The 1st keeps using on-off element, and it is located between the end of above-mentioned memory node and above-mentioned optical sensor; And

The 2nd keeps using on-off element, and it is located between the other end of reset line and above-mentioned optical sensor.

12. display device according to claim 10 is characterized in that,

Above-mentioned the 1st sensor pixel circuit and the 2nd sensor pixel circuit be shared 1 optical sensor between 2 kinds of circuit,

One end of above-mentioned shared optical sensor is connected to maintenance that above-mentioned the 1st sensor pixel circuit and the 2nd sensor pixel circuit comprise the respectively end with on-off element, and the other end is connected to above-mentioned reset line.

13. display device according to claim 11 is characterized in that,

Above-mentioned the 1st sensor pixel circuit and the 2nd sensor pixel circuit be shared 1 optical sensor between 2 kinds of circuit,

The 1st end that keeps with on-off element that one end of above-mentioned shared optical sensor is connected to that above-mentioned the 1st sensor pixel circuit and the 2nd sensor pixel circuit comprise respectively, the other end are connected to the 2nd maintenance that above-mentioned the 1st sensor pixel circuit and the 2nd sensor pixel circuit comprise the respectively end with on-off element.

14. display device according to claim 12 is characterized in that,

Above-mentioned the 1st sensor pixel circuit and the 2nd sensor pixel circuit between 2 kinds of circuit shared 1 read transistor,

Above-mentionedly shared read transistorized control terminal and be connected to an end and above-mentioned the 1st sensor pixel circuit of above-mentioned shared optical sensor and maintenance that the 2nd sensor pixel circuit comprises respectively a end with on-off element.

15. the driving method of a display device,

Above-mentioned display device has: display panel, and it comprises a plurality of display pixel circuits and a plurality of sensor pixel circuit; And light source,

The driving method of above-mentioned display device possesses following steps:

The step that above-mentioned light source was lighted with the stipulated time in 1 image duration;

The step of the 2nd control signal during the detection when the 1st control signal during the detection during to the sensor image element circuit output expression light source igniting is extinguished with the expression light source;

The 1st sensor pixel circuit that uses the sensor image element circuit to be comprised according to above-mentioned the 1st control signal, is surveyed light during the detection when light source igniting, the step of the light quantity that maintenance detects in the time of in addition;

The 2nd sensor pixel circuit that uses the sensor image element circuit to be comprised according to above-mentioned the 2nd control signal, is surveyed light during the detection when light source extinguishes, the step of the light quantity that maintenance detects in the time of in addition; And

During the detection when light source igniting with the detection of light source when extinguishing during beyond, undertaken from the step of reading of above-mentioned the 1st sensor pixel circuit and the 2nd sensor pixel circuit by the line order.

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